alpha channels

[galagast]

hmm.. as far as i can tell from the image, my hunch is, that dark part is a shadow... although you said you've excluded it from casting shadows.. the include/exclude list of a light will only affect the surface of the plane you've mapped, so basically, excluding it from your shadow casting light will only exclude your object from receiving light and shadows from other objects. To disable it from casting shadows, you could Right+Click on the plane, Properties, and uncheck Cast Shadows.

by script (just in case you're interested:) )
select your object and type this in the listener:

$.castShadows = false

set it to "true" if you want it to cast shadows again

also, If you have fog in there, you could also disable the atmospherics, as fog and transparent mapped objects usually has render problems without the right setting.

hope this helps :)

[yamicman]

galagast

Thanks for the tip, i'll give it a try when i have a chance a bit later.

the include/exclude list of a light will only affect the surface of the plane you've mapped

Would i be right in saying that the unmapped side of the plane could be casting this shadow then? It seems a bit strange as it does not have any polygons on the reverse face....

I have previously tried making this material double sided (i think thats right...) but all it did was diffuse the shadow into a dark blob around the characters feet, and across the wall behind her.

[Rockin]

First off, if I were you I would try composing images (using the outdated Videopost or Premiere).

Anyways you could have that problem which occurs when you try to render trees with branches created as polys with an aplha applied to them. Somehow the opacity doesn't work right in some conditions.. but I don't seem to remember the exactr cause so I may be totally wrong about this. Check the forum for opacity+tree+problem, you might get to the bottom of this.

Hope this helps somehow, I haven't been too specific:D.

[brzilian]

I agree with Rockin. This is someting better suited for After Effects/Premiere.

[andrewjohn81]

oh yes, the tree problem. That's easy. A shadow map doesn't take into consideration transparency. you can control that in mental ray I know for sure.

That doesn't sound like the problem though. They didn't want shadows there.

I totally agree with the compositing suggestions. Especially since you don't want shadows from the person.

[yamicman]

hmm....went to try galagasts suggestion, and it turns out cast shadows was already unchecked - i thought it sounded familiar, thanks anyway!http://www.cgtalk.com/images/icons/icon13.gif

Rockin, brzilian, andrewjohn81 thanks for the advice.

Its looking like compositing is the way forward then, will also have a look into the "tree thing" to see if that throws anything up.

I discussed this with one of our lecturers and he said that there was an inherent problem with the way max deals with alpha channels under certain lighting setups. His suggestion was to change from area shadows to raytrace and to cheat the "dither" effect. As the character isnt required to cast or recieve any shadows, the compositing method looks like it'll be the best way around this - rather than completely changing my lighting setup.

[robinb]

Area shadows can obey transparency, but it's turned off by default. Check the 'optimizations' rollout on the light. There's a transparency toggle in there that you can turn on, then the shadows work with transparency mapped planes like raytraced shadows do. Although in this case you don't want them anyway, it might be useful for something else.

[yamicman]

robinb
Yeah, i remembered about it after spending what seemed like an age trying to fix the problem. It seemed like the perfect (and ever so simple) solution! Unfortunatly switching the transparency toggle on didnt get rid of it....damn max...

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